RECURVES

Jim Hamm

Many people are surprised to learn that a recurved bow can be made from anything other than fiberglass laminations — the way all modern recurves are fashioned. But this style of bow is an integral piece of archery history, from the four thousand year old wooden bow found in the mud at the bottom of a lake in Italy, to the Turkish composite bows, to the sinew-backed bows made by the West Coast Indians. The beautiful recurves from the 1930's and 40's were the highwater mark of wooden bows, and today there is a resurgence of interest in these lovely weapons with the ancient lineage. An all natural-material recurve can rival the performance of the most up to date fiberglass bow on the market; good news for those who insist on true "traditional" in their tackle.

A recurved design holds some very important advantages, which helps explain why it has survived for so long.

Depending upon the degree of recurve, this type of bow shoots considerably faster than a straight bow of the same weight, the equivalent to shooting a bow 10% — 40% heavier. In fact, adding recurves to a design stands as the single most effective way to increase the cast per pound of draw weight. Because the string is under greater tension from the beginning of the draw, such a bow stores more energy early on, resulting in more total energy stored and faster arrow flight (see Bow Design and Performance in Vol. 1, for a complete discussion of the factors which contribute to an arrow's velocity).

The effect a recurved design has on arrow speed depends upon several factors. The more severe the angle of the recurve, and the higher the percentage of the limb which is devoted to the recurve, the more energy it stores. In general, the more the string contacts the tips of the bow the faster it will shoot an arrow.

Aside from the advantage of increased speed, recurved bows are usually shorter than straight-limbed bows, which makes them easier to transport and use in the field. Their maneuverability in a tree-stand or in thick brush improves considerably over a straight longbow's. The shorter design calls for shorter pieces of wood, which are naturally less difficult to find.

Recurves alleviate the stacking effect as the string angle at the tips increases during the draw. Though a recurve can add considerably to arrow speed, perhaps an equally important attribute may be in allowing a shorter bow to function without the normal stacking. These bows are very "smooth" to shoot, meaning that poundage increase per inch does not rise dramatically at the end of the draw.

From left to right the bows will shoot progressively faster, all else being equal, as the length and angle of recurve increases (courtesy Bear Archery and the Fred Bear Museum).

A recurve will have very little hand shock due to its shorter length. One reason for this is that the shorter limbs have less mass or physical weight; the less mass in a bow's limb, the less hand shock. And, as described in the Design and Performance chapter in Vol. 1, a recurve's limbs have vertical movement, in addition to the forward movement, as the tips coil up just as an arrow is released. Both of these factors contribute to a recurve's reduced jar or vibration.

Adding recurves is also an excellent way to increase the poundage of a bow which has been tillered to a lighter than desired draw weight. How much the weight rises depends upon the angle and length of the recurves, but it can often be increased by ten or fifteen pounds.

Though recurving a bow's tips is perhaps the single most effective way to improve efficiency and speed, as with almost every aspect of archery design something gained in one area means something lost in another. The increases in speed from a recurve are accompanied by decreases in stability and accuracy. This is due, in part, to the shorter limbs. Longer limbs tend to act as stabilizers, which hold the bow steady during and after the shot, while shorter limbs amplify any small errors of grip or arrow release. Another potential problem is that the higher string tension makes correct arrow spine more critical as the shaft must flex to a greater degree due to the harsh shove on the nock at the last moment of string contact, unlike the soft send-off of a longbow with a bit of string follow.

Though recurving a bow's tips will usually add speed, it is not a cure-all. In fact, in some cases, there is little or no benefit to recurves. For instance, the speed of a full-length bow of 67" drawing 50 pounds, outfitted with short, low-angle recurves, might well remain the same due to greater string follow resulting from increased strain on the limbs and thicker, more massive tips. At best, the speed would only rise by a couple of feet per second. However, if shortened to 60" in addition to the recurves, and re-tillered to the same weight, then such a bow will gain a bit of speed, about 5 fps. It will also show considerably more string follow, if it doesn't break outright from the additional strain on the working section of the limbs. Resolve this problem of durability and string follow by substituting wider limbs or using more elastic material. To reduce or eliminate string follow entirely, sinew-back the bow or make the working section of the limbs even wider and increase the total speed gains to around 10 fps. Or the handle can be set-back, in addition to all of the above, and the speed gain will be about 15 fps. As you can see, recurves alone are only modestly effective but become increasingly useful when added to shorter bows with wider or more elastic limbs, sinew-backing, and set-back limbs. The point is that each of these refinements add to the string tension early in the draw and improve the speed, but each also contributes to decreased stability and accuracy. There is no such thing as a free lunch, and nowhere is this more true than in archery designs.

For purposes of illustration, imagine a a 68" straight-limbed flatbow, with 1 1 /2" of string follow, at one end of the spectrum, and a 44" highly-reflexed and recurved Turkish bow at the other. Everything else being equal, the short bow will be much faster and the long bow much more accurate. As examples, short, highly-reflexed Turkish bows are on record as having shot arrows almost a thousand yards, while in the 1930's, Gilman Keasey used a longbow to place six out of six arrows into a nine inch circle at eighty yards. As we move from the longbow toward the shorter bow, the instability gradually rises and the angle and percentage of the recurve must gradually increase to reduce stacking. Still moving along the spectrum from the longbow toward the Turkish bow, the limbs must become wider, or be made from more elastic materials (such as horn/sinew), to withstand the increasing forces. As bow weight rises, limbs should also become wider or be of more elastic materials. There are no hard and fast formulas for constructing a recurve. An individual design depends upon bow weight, material, length of recurve, angle of recurve, percentage of the limb devoted to the recurve, speed requirements, and accuracy requirements, just to name some of the more important variables.

What, then, is the best design for a recurve? There have been many hours of long distance phone conversations between the authors of the Bozvyer's Bible series, agonizing over this very point. The merits of longbow vs. recurve, accuracy vs. stability, stacking vs. smooth-drawing have all been considered at great length. Though there is some divergence of opinion on this issue, based largely upon personal tastes. I'm prepared to go out on a limb here. Perhaps the best trade-off between speed and accuracy is a recurve of 60" to 64", measured before the tips are bent (this is for a 28" draw length). The smooth draw provided by the recurved tips gives the feel of a longer bow in terms of accuracy and stability. The speed gains will depend upon the configuration of the recurves, but the

A working recurve (top) and a static recurve.

The working recurve’s tip uncoils during the draw while the static tip remains stiff. Note how the string angle in relation to the tip is lower for the static recurve, thus giving a smoother draw with less stack.

Arrow will fly noticeably faster. Naturally, the resulting flatter trajectory makes aiming at different distances easier, and thus eliminates much of the factor most responsible for missed shots. This, combined with the smooth draw, allows a recurve of this length to be as accurate as a longbow, while giving greater penetration per pound of draw weight due to increased energy storage and speed. A recurve of this length may be best of both worlds.

Beyond the shooting factors, recurves are generally more trouble to construct. The manufacturing time of a bow can increase anywhere from a couple of hours to a couple of weeks, if the bow is also to be sinew-backed. A recurve places greater strain on the working section of a limb, making it more prone to breakage. Sinew-backing solves this problem, but raises some others, such as difficulty of construction and the effects of moisture upon the sinew and water-soluble hide glue which holds it in place. An all-wood recurve with no sinew backing is possible, though the working section of the limb must be appropriately wider to withstand the increased tension and compression. This adds to stave preparation time. Lining up the tips so the string tracks properly around the curves may present another difficulty and add to manufacturing time. And, since the working section of a recurved bow bends farther, the belly comes under more compression than a straight-limbed design, making it much more likely to chrysal, or exhibit compression fractures. This is especially true with any of the weaker woods such as ash or elm.

Recurves, in general, generate more noise when an arrow is released than straight-limbed bows, which can be a consideration for a hunter trying to place a tag on a wary game animal. The recurve's speed compensates for this somewhat, since a faster arrow gives an animal less reaction time, but it may be more difficult to dampen the sound of a recurve than a longbow.

Despite a few drawbacks, the first time you feel the smoothness of a recurve, and, most of all, see the arrow screaming toward the target, you'll instantly know what your next bow project will be.

So, let's roll up our sleeves and press forward into the actual construction.

There are two basic types of recurves; one which uncoils as the bow is drawn, or a working recurve, and one which remains stiff throughout the draw, or a static recurve.